Near-field enhancement of the mid-infrared field and its control by using metal nano-structures

中红外光为探测微观分子结构和高选择性激发分子振动提供了强有力的工具。因此，在中红外范围内的场增强，可以帮助开发方案的构象分析的大分子和控制分子的运动/反应。本研究以金属奈米结构为研究对象，借由透射光谱与电磁场分析，探讨金属奈米结构对中红外电磁波共振增强的光谱与时间响应。利用工作在中红外波段的扫描式近场光学显微镜测量了增强近场的空间分布。我们还研究了通过数值模拟的自由度在塑造增强近场的时间波形。

Mid-infrared light provides powerful tools in probing microscopic molecular structures and in exciting molecular vibrations with high selectivity. Field enhancement in mid-infrared range, therefore, may help developing schemes of analyzing conformations of macromolecules and controlling molecular motions/reactions. In this project, we investigate metal nano-structures which bring about resonant enhancement of the mid-infrared electromagnetic waves.By transmission spectroscopy and the electromagnetic field analyses, the spectral/temporal responses of the enhanced near-fields are clarified. The spatial distribution of the enhanced near-field is measured by using the scanning-type near-field optical microscopy working in the mid-infrared range. We also investigate by numerical simulations the degree of freedom in shaping the temporal waveform of the enhanced near-field.